Simplified floating deck pulse modulator

ABSTRACT

A floating deck pulse modulator to drive the modulating electrode of a transmitting tube such as a traveling wave tube or klystron in which the modulator includes two vacuum tubes with their circuits connected in series between the positive and negative electrodes of the transmitting tube and the mid point of the two vacuum tube circuits connected to the modulating electrode of the transmitting tube. By supplying the bias for one tube via a zoner diode connected to the second tube a great improvement is achieved over the prior art.

United States Patent Alsmeyer Apr. 23, 1974 [54] SIMPLIFIED FLOATING DECK PULSE 3,300,735 1/1967 Badger 332/7 MODULATOR 3,300,655 1/1967 Rosenbluth.. 307/297 X 3,259,855 7/1966 Massey 332/7 Inventor: Ralph ye e on, s 3,361,992 1/1968 Massey 332/7 [22] Filed: Jan. 24, 1973 v [2]] Appl. No.: 326,355 I Primary ExaminerAlfred L. Brody Related US. Application Data [63] Continuation of Ser. No. 216,752, Jan. 10, 1972, 57 ABSTRACT abandoned, which is a continuation of Ser. No. 2 1 3, 1970, abandoned, which is a A floating deck pulse modulator to drive the modulatcommuaton of 795,857 1969! ing electrode of a transmitting tube such as a traveling abandoned wave tube or klystron in which the modulator includes two vacuum tubes with their circuits connected in se- [52] Cl 332/13 307/297 457 ries between the positive and negative electrodes of the transmitting tube and the mid point of thetwo 2; vacuum tube circuits connected to the modulating 1 3 'fk Q electrode of the transmitting tube. By supplying the bias for one tube via a zoner diode connected to the d t t References Cited zecgrnartube a grea improvement IS achieved over the I I UNITED STATES PATENTS 1 3,274,515 9/1966 Badger 332 7 6 Claims, 1 Drawing Figure BIAS POWER SUPPLY ON KEYER BIAS POWER I SUPPLY INVENTOR RALPH L. ALSMEYE'R I ATTORNEY SIMPLIFIED FLOATING DECK PULSE MODULATOR This is a continuation of application Ser. No. 216,752, filed Jan. 10, I972, nowabandoned; which is a continuation of application Ser. No. 69,427, filed Sept. 3, 1970, now abandoned, which is a continuation of application Ser. No. 795,857, filed Feb. 3, 1969, now abandoned.

BACKGROUND OF THE INVENTION This invention relates to modulator circuits and more particularly to a modification of a common high vacuum (hard) tube floating deck pulse modulator commonly used to drive the modulating anode of a traveling wave or klystron transmitting tube. Prior art modulator circuits used for driving the modulating electrode of a transmitting tube have a number of rather specific and expensive power supply requirements. Such prior art circuits generally require a bulky, moderately high voltage screen power supply, a bias power supply for the on" tube and a continuous output from the on" keyer to overcome the bias during the pulse transmission interval. Because of the configuration of the modulator circuit of the present invention, the following advantages are achieved over the prior art: 1) The on keyer need supply only a short duration pulse; (2) There is no need for a bulky, moderately high voltage screen power supply; (3) No bias power supply is required for the on" tube; (4) There is no need for a continuous output from the on keyer to overcome this bias during the pulse transmission interval; (5 The SUMMARY OF THE INVENTION The above objects and advantages of the present invention are accomplished by providing a pulse modulator for a modulating anode tube of the type including a cathode, an anode and modulating means, said modulator comprising a first circuit connected to the modulating anode, said first circuit including means for initiating a pulse, a vacuum tube coupled to said pulse initiating means and to said modulating anode, and means for keying said pulse to said vacuum tube; a second circuit connected to the cathode said second circuit including means for initiating a pulse, a vacuum tube coupled to said pulse initiating means, means for keying said pulse to said vacuum tube, means for properly biasing the cathode, said means coupling the vacuum tube to the cathode; and a diode coupling the two vacuum tubes together in series for supplying the bias for the vacuum tube of the first circuit from the biasingmeans coupled to the vacuum tube of the second circuit.

BRIEF DESCRIPTION OF THE DRAWING The FIGURE is a circuit diagram of the modulator circuit employing the present invention.

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS The FIGURE includes a traveling wave tube shown schematically as 12 having a cathode l4 supplied from a power source applied at a terminal 15, a modulating anode 16, microwave structure 17 and a collector electrode 1 8. Coupled to the modulating anode ,16 are two vacuum tubes 20 and 22 which have the required constant current characteristics to charge and discharge the capacitance of the tube 12 and the associated circuitry with a linearly rising and falling voltage wave form. Although the vacuum tubes 20 and 22 are shown as being tetrodes, it should be understood that the other types of tubes could be employed'i'n the present invention. Coupled to each of the vacuum tubes 20 and 22 is a transformer 24 and 26 respectively each of which provides input pulses to the keyers 28 and 30 respectively. Connected between the pulse transformer 24 and the vacuum tube 20 is the off keyer 28 while connected between the pulse transformer 26 and the vacuum tube 22 is the on keyer 30.

The vacuum tube 20 has a cathode 32, a grid 34 connected to the off keyer 28, a screen grid 36 and an anode 38. The screen grid 36 is connected to the cathode 14 of the tube 12 via series connected zener diodes 39 and 40. Zener diode 40 provides the proper bias to the cathode 14 and modulating anode 16 of tube 12 to maintain the tube 12 cutoff during nonconductive periods. Tube 20 and its associated circuitry are mounted on a common floating off" deck 41.

The vacuum tube 22 includes a cathode 42, a grid 44 which is connected to the on keyer 30, a screen grid 46 and an anode 48. Coupled between the anode 48 and the screen grid 46 of the tube 22 is 'a resistor 50. The screen grid 46 is biased to the proper voltage by a zener diode 52. Another zener diode 54 is connecteddirectly between the anode 38 of the tube 20 and the cathode 42 of the tube 22. Tube 22 and its associated circuitry are mounted on-a common floating 370m" deck 55 which is connected to the modulating anode 16. The operation of circuit 10 is as follows. Vacuum tube 22 is the on" tube and vacuum tube 20 is the off tube. During the on period of the transmitted pulse initiated through the transformer 26, tube 22 is conducting while tube 20 is cut off. Conversly, during the interpulse period, tube 20 is conducting and tube 22 is cut off. During the interpulse period tube 20 is biased so as to draw a small amount of current through resistor 50, zener diode 52 and zener diode 54. The voltage drop across zener diode 54 is fed to the grid 44 of tube 22 and holds tube 22 at or beyond cut off. The voltage drop across zener diode 52 maintains the screen grid 46 of tube 22 at the desired potential.-

To initiate an output pulse, a pulse is triggered from pulse transformer 26 through the on keyer 30 to the grid 44 of the on" tube 22. This pulse drives the tube 22 toward saturation and needs to be maintained only long enough to allow the stray capacitance of the modulating anode 16 of tube 12 and associated circuitry to discharge to ground potential. Simultaneously, a pulse of sufficient amplitude for cut off is supplied by the off keyer 28, which is triggered through the pulse transformer 24 to the grid 34 of tube 20. This pulse must persist for the duration of the output pulse. The cut off of current from the anode 38 of tube 20 causes the voltage drop across zener diode 54 to go to zero pulse, the output voltage of the off keyer 28 is re versed to cause tube to conduct heavily and recharge the load capacity to the tube cathode 14 potential. The resumption of current flowing through zener diode 54 simultaneously cuts off tube 22.

The advantage of this circuit over the prior art lies in the simplicity of the circuitry of the on deck. The on keyer 30 need supply only a sh'ortduration pulse, and the use of zener diode 52 eliminates the need for a bulky moderately high voltage screen power supply. No bias supply, as such, is required for the on tube 22, nor is a continuous output from the on keyer 30 required to overcome this bias during the pulse length.v These simplifications in circuitry allow the physical size of the on deck and the isolation transformer 26 which supplied it to be decreased. This decreases the circuit capacitance to ground and the losses associated with discharging and charging this capacitance for each pulse. The simplification also improves the inherent reliability of the equipment by the reduction of required component parts.

I claim:

1. In combination:

an electron discharge device;

a source of electrical power connected to said device;

and

means coupled to said electron discharge device for controlling the discharge of current through said device comprising a first signal control device having at least a control electrode and two other electrodes, a second signal control device having at least a control electrode and two other electrodes, means connecting said devices in series through a circuit comprising a constant voltage device, means for supplying an electrical bias derived from said constant voltage device to said control electrode of said first device, and means for coupling control signals to said control electrodes.

2. The combination in accordance with claim 1 wherein an additional bias voltage is connected to said second control device to produce an electrical bias with respect to said controlelectrode of said second control device.

3. The combination in accordance with claim 2 wherein a signal supplied to the control electrode of said first control device at least in part causes said electron discharge device to conduct.

4. The combination in accordance with claim 3 wherein the signal supplied to the control electrode of the second control device at least in part causes said electron discharge device to cease conduction.

5. The combination in accordance with claim 4 wherein the signal supplied to the control electrode of said second control device comprises a pulse which overlaps in time a signal pulse supplied to the control electrode of said first control device.

6. The combination in accordance with claim 1 wherein said control devices are vacuum tubes.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,806,836 Dated April 23, 1974.

Inventor(s) Ralph L. Alsmeyer It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

On the title page, it should be stated Assignee: Raytheon Company, Lexington, Massachusetts In the Abstract, "zoner" should be zener Column 1, before the' "Background of the Invention" insert The invention herein described was made in the course of and under a contract or subcontract thereunder'with the United States Army Missile Command.

Column 2, line 38, delete "37" and insert before 1' n" H.

Column 2, line 55, after "pulse" second occurrence, insert of microwave energy from the tube 12 through a conventional output waveguide or coaxial coupling (not shown) Column 2, line 62, after "20" insert by having one end of the secondary winding of transformer 24 connected through "off" key 28 to grid 34 and the other end returned to the cathode 32 throughazener bias diode 39a Column 2, line 62, at the end of the proposed correction, insert the following: ,which is immediately to the left of zener diode 59 Signed and sealed this 15th day of April 1975.

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1. In combination: an electron discharge device; a source of electrical power connected to said device; and means coupled to said electron discharge device for controlling the discharge of current through said device comprising a first signal control device having at least a control electrode and two other electrodes, a second signal control device having at least a control electrode and two other electrodes, means connecting said devices in series through a circuit comprising a constant voltage device, means for supplying an electrical bias derived from said constant voltage device to said control electrode of said first device, and means for coupling control signals to said control electrodes.
 2. The combination in accordance with claim 1 wherein an additional bias voltage is connected to said second control device to produce an electrical bias with respect to said control electrode of said second control device.
 3. The combination in accordance with claim 2 wherein a signal supplied to the control electrode of said first control device at least in part causes said electron discharge device to conduct.
 4. The combination in accordance with claim 3 wherein the signal supplied to the control electrode of the second control device at least in part causes said electron discharge device to cease conduction.
 5. The combination in accordance with claim 4 wherein the signal supplied to the control electrode of said second control device comprises a pulse which overlaps in time a signal pulse supplied to the control electrode of said first control device.
 6. The combination in accordance with claim 1 wherein said control devices are vacuum tubes. 